Teaching Case

A 49-year-old woman diagnosed with systemic sclerosis complains of dysphagia.

Contrast-enhanced thoracic CT showed an aberrant right subclavian artery arising distal to the left subclavian artery and passing posterior to the oesophagus – arteria lusoria. The oesophagus was mildly dilated immediately proximal to the arterial origin, and on its distal part. Mediastinal lymph node enlargement and moderate pericardial effusion were also noted.   

Chest HRCT showed a typical fibrotic NSIP pattern: symmetric reticulation with subpleural and peribronchovascular distribution, predominant on the lower lobes, associated with traction bronchiectasis, discrete ground glass opacities and interlobular septal thickening. A normal variant of the right upper lobe was also identified – azygos lobe.

During the barium oesophagogram the oesophagus was mildly dilated (3.5 cm maximum diameter). The aberrant right subclavian artery caused an extrinsic compression on the posterior oesophagus wall, crossing diagonally upwards and to the right.  

Background: Systemic sclerosis is an immune-mediated multi-systemic disease, having a higher mortality than any other rheumatic disease [1]. The definite diagnosis is established based on the 2013 criteria for the classification of systemic sclerosis by the European League against Rheumatism (EULAR), which considers the presence of interstitial lung disease (ILD).

The left aortic arch with an aberrant right subclavian artery is the most common aortic arch anomaly, occurring in 0.5-2.5% of people [2]. Most frequently, the artery crosses posterior to the oesophagus, although passing between the oesophagus and trachea, or anterior to the trachea is also possible. It is asymptomatic in most of the cases. When symptomatic, it usually causes dysphagia, which is then called dysphagia lusoria.   

Clinical perspective: Gastrointestinal tract involvement in systemic sclerosis is almost universal [1]. However, severity and clinical manifestations vary. On the other hand, dysphagia lusoria is typically a dysphagia to solids without difficulty in swallowing liquids [2]. Although oesophageal manometry is the gold standard for motility disorders, barium oesophagogram has an important role as a dynamic examination, being frequently used to evaluate dysphagia lusoria.

Imaging perspective: Thoracic CT is the most important tool to evaluate lung involvement in scleroderma, which usually manifests as NSIP. In fact, a simple semi-quantitative classification system (extent of disease below or above 20%) was shown to be of prognostic importance [3]. Mediastinal lymph node enlargement is also a frequent finding. In addition, a dilated oesophagus on CT in a patient with systemic sclerosis is suggestive of oesophageal involvement. Cardiac involvement in scleroderma is often subclinical, but pericardial effusion is not an uncommon finding [4].

The presence of the arteria lusoria is described on the barium oesophagogram as a fixed narrowing on the posterior wall of the oesophagus, crossing diagonally upwards and to the right, at the level of the aortic arch – also known as the Bayonet sign [5].

Outcome: Although surgical treatment is available for dysphagia lusoria, it is usually reserved for patients with arteria lusoria aneurysm, due to its high complication rate. Gastrointestinal manifestations of systemic sclerosis are treated conservatively. In our case, the patient improved with symptomatic therapy (proton pump inhibitors).

Teaching points: Systemic sclerosis is a multisystemic complex disease requiring an integrated multidisciplinary approach. It is important to include all imaging findings available in order to reach the final diagnosis. Conventional imaging modalities may still play an important role in clinical practice.

Written informed patient consent for publication has been obtained.